Installing an undermount bathroom sink

Our undermount bathroom sink was installed under a granite counter. The sink developed a crack. When we tried to remove the sink to replace it, a couple of the brackets that helped to hold the sink came off when we pried out the sink. they appear to have been mounted to the granite underneath with some sort of plastic-like adhesive. We got a new sink to put in but don't know what to use to put those brackets back on. Any advice?